The InSAR technique involves examining pairs of radar images of the same landscape to determine changes in the land surface over very broad regions to within a couple of inches (5 centimeters).

The satellites can thus detect slight deformations in the Earth's crust, which may indicate built up strain prior to an earthquake.

Scientists envision the Global Earthquake Satellite System as a dedicated network of InSAR-equipped satellites to monitor fault zones around the world.

"These observations would allow us to test our knowledge of the physics of the earthquake process by comparing the observed motion of the Earth's surface with realistic models of fault system behavior," Raymond said.

The satellites would utilize something known as L-band InSAR. L-band refers to the wavelength of the radar signal. In this case, it is about 9 inches (24 centimeters). From the technology standpoint, Raymond said, L-band InSAR in low-Earth orbit is ready to go.

The space shuttle flew a mission in February 2000 that used the technology to create a topographic map of the Earth. A proposal to launch an InSAR-equipped satellite is currently before NASA. Scientists hope that within 20 years, several more satellites will launch.

Raymond said that while a single InSAR-equipped satellite would be useful, a constellation of such satellites would deliver an extremely dense data set for use by earthquake prediction scientists.

As scientists wait for the network of InSAR satellites to be realized, sophisticated global positioning system, or GPS, networks are being used to monitor the Earth's crust. This information is helping scientists create models of complex Earth deformation.

Other Stress Relief

Many of us know that earthquakes are a sudden release of energy caused by the sliding of a patch of the Earth's crust along a fault, such as the infamous San Andreas Fault near Los Angeles, California.

In such cases, there is no shaking and damage to buildings. Scientists are uncertain as to how much of the overall stress in the Earth is released in this manner, but InSAR may help answer that question.

"An InSAR system would be able to detect these events globally and clarify their role in the total strain budget," Raymond said, adding that the technology would also shed light on the phenomena that control the differences in stress relief between damaging and benign seismic shifts.